Charging to 100% and regaining lost range

[dan_b]

I've had my Tesla almost 3 years now and just over 30k miles so far.
In that time I've always preferred the % battery charge indicator to miles of range as it just seems more useful. When I got it, 100% range showed at 305 miles. (pre-octovalve/heatpump efficiency gains!), so in my brain I always did a 1%= 3 miles calculation and just left it at that.

In that time also, I almost never did a full 100% charge - basically only if I knew I had a "big drive" the next day would I go to 100%. I guess I'd probably done 3 or 4 100% charges in all of that time.

About 6 weeks ago, I had a road trip for the first time in a long time, so did a 100% charge. I tapped on the % battery charge and it said 290 miles I guess I was a bit surprised to have seen 15 miles of range escape. I then read the user manual and it says that it's actually recommended to charge to 100% regularly - just to not do that and leave it at 100% SoC without driving it.. So

Last week I did another 100% charge and this time the GOM said 294.

Today I've done another one and now the GOM is saying 298.

Looks like the BMS is doing some good work with cell balancing and maybe I haven't "lost" that range after all?

[Mart]

That's good to know, I hadn't realised/heard that before.

"Real men don't read user manuals."

[Bugtownboy]

"Real men don't read user manuals."

Mart, need the reference for that, may come in useful

[AE-NMidlands]

apart from
"if all else fails, read the instructions!"
A

[Tinbum]

It amazes me how many people ask questions that are answered by the manual. To be honest it really annoys me.

The first thing I do is read the manual and that's normally before I've even bought the item!!

edit- also people asking questions without going a quick Google first and also asking questions without giving any details of their set up. Rant over

[greentangerine]

Presumably it's balancing the cells and hence the increase in capacity.

Far too much fretting about battery management and maximising range with EVs; just use it as you would an ICE car and enjoy the experience.

[nowty]

I doubt its increasing real range, just apparent range, more of a recalibration of the BMS to make it more accurate, rather than being more conservative over time because of less battery level data points to calculate from.

And I doubt that balancing of the cells is only performed at the top end, that's old tech, were you blead off high cells via zenner diodes through resistors. More likely like my active cell balancers I use on my re-used home battery cells which uses the power from higher cells to charge any adjacent lower cells.

There is a way of calculating the effective size of the battery pack so you can work out the degradation over time, I did it when mine was new and it was about 74.8 kWh out of a nominal 75kWh pack. I'll have to do the calculation again soon to see if there has been any difference.

I cannot remember the website I found it, but I took a screen shot of the instructions. You charge the car full, then drive it normally for about 20 miles, then go to the energy screen and do the calculation. I did the calculation several times when new and it came put just under 75kWh every time. I'm doing a fish run tomorrow so I might have a go at it again.

[Ken]

I think to get an accurate fig one needs to do a round trip so as to minimise effect of wind and elevation.

[nowty]

I think to get an accurate fig one needs to do a round trip so as to minimise effect of wind and elevation.

That's exactly what I am doing today in a couple of hours time. Currently doing the final charge to 100% and the cabin will be pre-conditioned before I set off. Making sure its just over a 15 mile journey and set the average to last 15 miles. Might not be fully comparable with my initial measurements as it was late sept so it was cooler with less aircon on.

Tesla have also changed the software several times, there was a report where Tesla had reduced the battery float voltage which resulted in reduced range. Then they backed it out or at least partially restored to the previous levels.

[nowty]

Just done my test drive, charged to full but only showed 97%, preconditioned the cab via the charge cable, it was pulling about 1kW from the charger to do this, although the APP does not show any transfer. Drove an 18 mile round trip with two stops (fish market and supermarket). Half was at 30mph to 50mph and half at 70mph, mostly flat.


So when new (first month) I did the test and calculation 3 times and it was around 74.7kWh to 74.8kWh

Now its 226 x 293 / 0.9 = 73,576 Wh or 73.6 kWh

Car is under 10 months old with a little over 6k miles.

Would be interesting if dan_b does this test as he's done 5 times my mileage and his car is 3 times the age. Would the calc come out closer to 70 kWh ?
Mines a China model but I suspect dan_b is a USA model ?
I was a bit miffed when I got mine as I thought it was having a 82kWh pack, but it seems they only put that into the performance model from China when I ordered mine. The USA LR model (at the same time) already had the 82kWh pack.